The Weeks of Nights of Full-Moon is a simple way of reckoning a period of usually 3 nights that have a full moon. It was developed by Simon Cassidy.

Alternate full moons are placed in one of two strands. A full moon period begins exactly 8 weeks after the end of previous full moon period in the same strand.

These full moon periods are dispayed on a page that has the two strands each with 16 full moon periods in it. Every full moon period has 3 nights, except for one in each strand on a page which has 4 nights. These 16 periods of 3 or 4 nights cover 49 nights of full moon, which is exactly 7 weeks hence it is called the week of weeks of nights of the full moon.

If the 4-night full moon periods were to keep the same position on every page. The mean lunation reckoned would be 29 17/32 days, which is a little too long. To correct this every 3rd 4-night full moon period in each strand is delayed one place (2 lunations) down the strand. If this results in a 4-day full moon period disappearing off the bottom of the strand. It then appears at the top of the strand after missing one page. This results in a more accurate mean lunation of 29 26/49 days.

This is very similar to the Yerm Lunar Calendar and like it shows little variation of the actual full moon with respect to the calendar.

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